Thermal switch



June 12, 1945. w. HILL 2,378,080

THERMAL SWITCH Original Filed Feb. 24; 1943 2 Sheets-Sheet 1 I n l/en tor 6' J0 J/ I Walk/e7. H020 By 2mm June 12, 1945. w. HILL 2,378,080

THERMAL swITcH Original Filed Feb. 24, 1945 2 Sheets-Sheet 2 Inventor Wa/Zher HLZZ/ y Mad W E Patented June 12, 1945 UNITED STATES PATENT OFFICE 1943, Serial No. 494,750

1 Claim.

This invention relates to new and useful improvements in thermal switches for fire alarm systems and the like, the same being a division of my co-pending application Serial No. 476,935, filed-February 24, 1943, for Signal system.

The principal object of the present invention is to provide a thermal switch which will operate promptly upon submission to heat of a predetermined temperature, for the purpose of closing a signal system or circuits of other nature.

Another important object of the invention is to provide a thermal switch which can be manufactured in convenient useful units and which can be installed in homes and elsewhere by unskilled labor.

Other objects and advantages of the invention will become apparent to the reader of the following description.

In the drawings:

Figure 1 is a top plan view of the switch.

Figure 2 is an end elevational view.

Figure 3 is a transverse sectional view taken on the line 3-3 of Figure 1.

Figure 4 is a longitudinal sectional view through the device.

Figure 5 is a perspective view of a sheet of destructible material such as is employed in the switch.

Referring to the drawings wherein like nu merals designate like parts, it can be seen that numeral 6 generally refers to the thermal switch. Each of the switch units consists of a frame 1 which may be of any suitable material and each corner of this frame has a bracket 8 apertured to receive suitable securing elements for securing the thermal switch unit to the ceiling as shown in Figure 2.

At the inner side portions of opposed sides of the frame I are eyes 9, and back and forth through these eyes is laced a conductor i0. One end of this conductor is anchored as at ll while the other end passes through a bushing ii in the frame I.

The conductor I is located at the lower side of a sheet I! of Cellophane or some other inflammable material. while under this sheet is located a conductor wire ll which is disposed back and forth in the manner substantially shown in Figure in a direction transverse to the flights of the conductor It. The conductor i4 is an- Divided and this application July 14,

chored at one end as at l5, while its opposite end passes through the bushing i2.

The wires and 3| to the conductors i4 and I0, respectively, extend to one part of a signal or warning circuit, or a circuit of some other character.

Inasmuch as the sheet of material i3 is of fire destructible material, the switch will be used in most instances as a switch in a fire alarm circuit.

In the operation of this switch, it can be seen that should a fire occur in a room or elsewhere, where one of the switches is located, the fire will destroy the sheet [3 of the corresponding thermal switch 6, to the end that the conductor M will lower to engage conductor l0 and close a circuit or system so that an indicator or alarm will become efiective.

While the foregoing specification sets forth the invention in specific terms, it is to be understood that numerous changes in the shape, size and materials may be resorted to without departing from the spirit and scope of the invention as claimed hereinafter.

Having described the claimed as new is: v

A thermal switch unit comprising an open frame, means to attach the frame to an overhead support so as to mount the frame in a horizontal position, a conductor having a zig-zag bare end portion extended back and forth in spaced flights between and connected to opposed members of the frame at one of its ends and at the ends of the flights thereof to assume a taut horizontal position in the frame, an inflammable sheet of electrical insulating material disposed in the frame and resting on and covering said bare end portion of the conductor, a second conductor wire having a zig-zag bare end portion extended in spaced flights back and forth within the frame upon the inflammable sheet and with its flights transverse to the flights of the first-named conductor, the flights of the second-named conductor being unattached to the frame and free to lower by gravity and engage those of the first-named conductor for closing a circuit when the inflaminvention, what is mable sheet is destroyed by flire, and an insulator 

